1. Field of the Invention
The present invention relates to a lens barrels and, more particularly, relates to a structure for assembling/disassembling a lens barrel having a lens group guided in an optical axis direction of the lens group.
2. Description of the Related Art
It is desired that lens barrels have a construction that can be readily disassembled for the ease of replacement of the photographing lens group.
For example, the assignee of the present application has proposed a zoom lens system that achieves high zoom ratio while maintaining the advantage of constructing a smaller lens systems (U.S. patent application Ser. No. 09/534,307, Japanese Patent Application No. Hei 11-79572). This zoom lens system has following characteristics: it includes a plurality of movable lens groups for varying the focal length; at least one of the lens groups is a switching lens group which includes two sub-lens groups, one of the sub-lens groups being a movable sub-lens group that can be selectively positioned at either one movement extremities in the optical axis direction with respect to the other sub-lens group; the movable sub-lens group of the switching lens group is positioned at an extremity of a short-focal-length zooming range, from the short focal length extremity to an intermediate focal length, and at the opposite extremity of a long-focal-length zooming range, from the intermediate focal length to a long focal length extremity; and zoom paths of the switching lens group and the other lens groups are discontinuous at the intermediate focal length and are defined to focus on a predetermined image plane corresponding to the position of the movable sub-lens group.
It is especially required that the switching lens group unit, including the lens guide mechanism (linear guide mechanism), can be readily assembled or disassembled in the mechanical construction of the lens barrel used in such a zoom lens system since guiding each sub-lens group of the switching lens group, which provides a single lens group, requires an individual guide mechanism.